OFFSET
0,1
COMMENTS
a(1) has been checked by the direct computation of the Wiener index (using Maple).
REFERENCES
A. R. Ashrafi and H. Shabani, Computing Padmakar-Ivan index of four classes of dendrimers, Bulgarian Chem. Comm., 44, N0. 2, 2012, 127-130.
FORMULA
a(n) = -74142 + 2^n*(241658-45756*n)+4^n*(115320*n - 167090).
G.f.: 2*(213 +52522*z + 66470*z^2 -419644*z^3-33200*z^4)/((1-z)*(1-2*z)^2*(1-4*z)^2).
MAPLE
a := proc (n) options operator, arrow: -74142+2^n*(241658-45756*n)+4^n*(115320*n-167090) end proc: seq(a(n), n = 0 .. 20);
CROSSREFS
KEYWORD
nonn
AUTHOR
Emeric Deutsch, Jul 13 2013
STATUS
approved